1, Field of the Invention
The present invention relates to a method and apparatus for removing liquid carrier in an image forming apparatus. More particularly, the present invention relates to a method and apparatus for removing liquid carrier from an intermediate transfer medium by evaporating the carrier at a low temperature.
2, Description of the Related Art
In general, image forming apparatuses are classified into either dry-type image forming apparatuses that use a powder developer such as toner or wet-type image forming apparatuses that use a liquid developer, which is a mixture of powder toner and a liquid carrier.
Dry-type image forming apparatuses have the disadvantage that they produce toner dust, which can be messy and should not be consumed. Dry-type image forming apparatuses also have limitations with respect to the image quality of color images. As a consequence, research on wet-type image forming apparatuses has become more active.
Wet-type image forming apparatuses can be further classified as either monochrome image forming apparatuses that produce a single color image (typically, black) or color image forming apparatuses that produce a color image. Typical color image forming apparatuses use magenta, cyan, yellow and black developers to form a color image.
In a wet-type image forming apparatus, as is well known to those of ordinary skill in the art, an electrostatic latent image is formed on an image carrying medium by a laser beam projected by a laser scanning unit. Prior to scanning, the image carrying medium is electrically charged by an electrifying unit to a predetermined potential. The electrostatic latent image is developed using a developer and the developed image is transferred onto a printing medium to form a visible image. In color image forming apparatuses, a plurality of single color images are formed on a plurality of image carrying mediums by using developers of different colors. The single color images are transferred and overlapped onto an intermediate transfer medium, such as an intermediate transfer belt (ITB), to form a full-color image. The full-color image formed on the intermediate transfer medium is then transferred onto a printing medium. The printing medium with the transferred full-color image passes through a series of fixing processes and is then discharged from the image forming apparatus.
Here, the developer is an ink mixture having a predetermined color and comprising a magnetic powder toner and a liquid carrier. The ink is supplied to a developing unit through a dedicated ink cartridge, and developed on the electrostatic latent image formed on the image carrying medium.
However, in such a wet-type image forming apparatus, the intermediate transfer medium and the full-color image transferred onto the intermediate transfer medium may be saturated with the liquid carrier. The carrier included in the intermediate transfer medium is transferred to the printing medium together with the full-color image, thereby deteriorating transfer efficiency. In addition, the liquid carrier transferred onto the printing medium evaporates during a fixing process; however, large amounts of electricity are required to evaporate the carrier in the required short time frame. Furthermore, the processes and devices for collecting and purifying the evaporated carrier are complicated and increase manufacturing costs.
Accordingly, there is a need for an improved method and apparatus for removing liquid carrier in a wet-type image forming apparatus.